1. Field of the Invention
The present invention relates generally to an assembly method for biofilm support structure modules used in the treatment of wastewater and to an apparatus used to effect this method. In particular, the present invention is directed toward a fast, simple method of assembling the biofilm support structure modules after shipping of individual components, saving on shipping costs and cutting down on assembly time compared with currently used assembly methods. It is also directed to an assembly fixture that is used to assemble the biofilm support structure modules from biofilm support structure sheets and module retainer tubes.
2. Background and Description of the Related Art
Biofilm refers to a layer of biologically active organisms which digest and hence eliminate organic matter from wastewater, thereby purifying the wastewater. In advanced applications of biofilm technology, biofilm is grown on or in a medium which acts as a carrier for such organisms. In some cases, the biofilm media are inorganic sheets or support structures which provide increased surface area on which the biofilm can grow.
Biofilm support structures have been used in wastewater treatment processes for more than fifteen years. These structures predominantly made of plastic, usually are installed in trickling filters or placed in wastewater treatment aeration tanks to treat and purify wastewater. Biofilm support structures are sold assembled in modules for small scale home wastewater treatment plants and in larger sizes for commercial wastewater treatment plants. Assembly of the modules takes place in factories or in the field using a gluing method. Using this method, individual sheets of the biofilm support structure are layered on top of one another, with waterproof glue spread between each layer to bind them. The biofilm support structure sheets are not flat. Rather, each sheet has a texture that is pleated in two roughly perpendicular directions, forming alternating rounded peaks and valleys. In assembled form, adjacent sheets are oriented in corrugated fashion. That is, the orientation of adjacent sheets alternates so that valleys in a particular sheet rest on peaks of the sheet below it. The peaks of the upper sheet in turn support the valleys of the sheet placed on top of it. The sheets alternate in this manner in order to provide more available surface area for the growth of biofilm. This in turn provides more treatment surface area for wastewater. In certain wastewater treatment applications the entire biofilm support structure modules are submerged in the fluid being treated within a wastewater treatment plant.
Because of the corrugated arrangement of the assembled biofilm support structure sheets in the assembled module, the factory assembled modules have a large shipping size, causing unnecessarily high freight costs. This cost could be reduced by assembling the modules in the field rather than before shipping. However, if the modules are assembled in the field using a gluing method, trained workers must travel to the assigned location to perform the assembly. The cost of the labor involved in this solution is ultimately much more expensive than the shipping costs incurred following assembly in the factory. A new method of assembling the biofilm support structure modules is therefore needed. This new method must be able to be performed in the field, but must be simple enough that trained workers are not necessary to carry it out, or must be quick and simple enough that assembly can be effected at a distribution plant after reception of the shipment from the factory.